[The goal-oriented project "pathology of environmental pollutants" (M.U.R.S.T. 40%)]

The purpose of this study was to estimate to toxicity bound to effluent water, pore water and bed sediment sampled twice during 1994 (spring and autumn) from 16 tributaries of Po river. Toxicity was determined by using a battery of bioassays (Artemia salina, Dugesiagonocephala and Thamnocephalus platyurus) and a battery of phytoassays, including Oryza sativa and Triticum sativum. Results show that practically no toxicity is found in effluent water, mild adverse effects are obtained with sediment pore water, while the most harmful compounds are those bound to sediment particles. These data strengthen the hypothesis that sediment is the true historical memory of the ecotoxicological conditions of a water body. Finally, the map of our results illustrates that pollution severity is progressively increasing from western to eastern tributaries in Po river valley.